ResultReceiver可以简单实现不同组件之间的消息分发。

使用场景：用于service接收activity的回调

比如activity需要返回结果给启动它的service，可以这么实现：
service.java

public ResultReceiver resultReceiver = new ResultReceiver(handler) {
    @Override
    protected void onReceiveResult(int resultCode, Bundle resultData) {
        super.onReceiveResult(resultCode, resultData);
        Log.i(TAG, "onReceiveResult, resultCode:" + resultCode + ", resultData:" + resultData.toString());
    }
};

// 启动activity，传入resultReceiver
Intent intent1 = new Intent(getBaseContext(), MyActivity1.class);
intent1.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent1.putExtra("result_callback", resultReceiver);
startActivity(intent1);

activity.java

public void onClick(View view) {
    ResultReceiver resultReceiver = getIntent().getParcelableExtra("result_callback");
    Bundle resultData = new Bundle();
    resultData.putString("msg", "这是来之activity的调用");
    resultReceiver.send(0, resultData);
}

触发onClick，会看到打印：

2023-09-11 16:58:40.449  5303-5303  MyService1                          com.ericcode.codetest                I  onReceiveResult, resultCode:0, resultData:Bundle[{msg=这是来之activity的调用}]

证明service收到了来自activity的消息。

使用场景：用于组件互发消息

service.java

public ResultReceiver resultReceiver = new ResultReceiver(new Handler()) {

    @Override
    protected void onReceiveResult(int resultCode, Bundle resultData) {
        super.onReceiveResult(resultCode, resultData);
        Log.i(TAG, "onReceiveResult, resultCode:" + resultCode + ", resultData:" + resultData.toString());
        ResultReceiver activityResultReceiver = resultData.getParcelable("result_callback");
        if (activityResultReceiver != null) {
            Bundle reply = new Bundle();
            reply.putString("msg", "这是来着service的消息");
            activityResultReceiver.send(0, reply);
        }
    }
};



// 启动activity，传入resultReceiver
Intent intent1 = new Intent(getBaseContext(), MyActivity1.class);
intent1.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent1.putExtra("result_callback", resultReceiver);
startActivity(intent1);

activity.java

public ResultReceiver resultReceiver = new ResultReceiver(new Handler()) {
    @Override
    protected void onReceiveResult(int resultCode, Bundle resultData) {
        super.onReceiveResult(resultCode, resultData);
        Log.i(TAG, "onReceiveResult, resultCode:" + resultCode + ", resultData:" + resultData.toString());
    }
};

public void onClick(View view) {
    ResultReceiver serviceResultReceiver = getIntent().getParcelableExtra("result_callback");
    Bundle resultData = new Bundle();
    resultData.putString("msg", "这是来之activity的调用");
    resultData.putParcelable("result_callback", resultReceiver);
    serviceResultReceiver.send(0, resultData);
}

触发onClick，会看到打印：

2023-09-11 17:51:12.316 14795-14795 MyService1                          com.ericcode.codetest                I  onReceiveResult, resultCode:0, resultData:Bundle[{msg=这是来之activity的调用, result_callback=com.ericcode.codetest.resultreceiver.MyActivity1$1@7b303fe}]
2023-09-11 17:51:12.319 14795-14795 MyActivity1                         com.ericcode.codetest                I  onReceiveResult, resultCode:0, resultData:Bundle[{msg=这是来着service的消息}]